Weighing device



Eea; 28, 93?. M. A. WECKERLY WEIGHING DEVICE Filed Feb. le, 1934 5 Sheets-Sheet De@ 28, 1937. M. A. WECKERLY 2363,40@

WEIGHING DEVICE Filed Feb. 1e, 1954 3 sheets-sheet 2 /Nl/ENTOR ljecz:a 2S, 1937., m. A. WEGKERLY WEIGHING DEVICE Filed Feb. l5, 1954 3 Sheets-Sheet 5 Mor/ A. Weder/g INI/ENTO/e A TTORNEY Patented Dec. 28, 1937 UNITED STATES PATENT' oi-Flcs WEIGHING DEVICE Application February 16, 1934, Serial No. 711,498

Claims.

This invention relates to weighing devices and particularly to devices adapted to continuously weigh predetermined quantities of material within a given unit of time. Such machines find wide 5 application in industry, in continuous hatching operations and in continuously delivering accurate amounts of material in blending processes. Therefore, the principal object ci my invention is the provision of improved means for accurately feeding a predetermined quantity of material in a given unit of time.

Another object is the provision of improved means, whereby a. travelling conveying means is continuously loaded with definite uniform amounts of materials.

Still another object is the provision of improved electrical meansv non-reactively controlled by a weighing scale for controlling the speed of the material feed stream; and

'A still further object is the provision of imfproved means, whereby material feeding means having a predetermined rate of speed are nonreactively mounted on the load receiver` of a weighing scale. l

Referring to the drawings:

Figure I isa iront elevational view of my improved device.

Figure 11 is a plan View of the load receiver oi. the scale employed therein showing the relative 3o position of the constant speed conveying means, and as seen substantially from a position along the line lis-II of Figure-lill. f

Figure III is a side elevational view oi the device seen substantially from a position along the line @II-Ill of Figure I, and

Figure lIV is a diagram depicting the electrical circuits.

Referring to the drawings in detail, the device comprises a vibratory material feeding inea-ns l 40 suitably stationed on a stand or other support 2, which is located so that material flowing from a.

bin (not shown) through a spout 3 and hopper.

l is delivered to a belt conveyor 5. This mate rial feeding means comprises a conduit 6 which is mounted on flexible supports 1, which are 1ocated so that impulses from a reciprocating motor 8, are transmitted to the conduit 6, thus imparting a longitudinal vibration thereto, so that any material thereon is advanced with each impulse a. distance which is proportional to its amplitude'. Tfhe motor 8 is of a. type in which the amplitude of its reciprocatory motion may be varied as desired. Since such feeding means are known in the art and also described in my co- '55 pending application Serial No. 641,133 of which this application is to be considered a continuation in part, it is deemed unnecessary to describe its mechanical structure in greater detail.

The weighing device which is used in connection with the feeding means is fully described 5 and disclosed in U.' S. Patent 1,768,478 to H. O. Hem, and is, therefore, described herein on'ly so far as is necessary to fully disclose my invention.

In this device a base plate 9 is provided with upstanding extensions i0 in whichbearings Il le are seated, a main lever l2 is mounted with its fulcrum pivots i3 upon these bearings i l. Pivots M and i5 xed in the lever i2, in spaced relation to the fulcrum pivots i3, support load and counterpoise receiver spiders ,l5 and Il respectively. l5 Posts i8, which are studded into the upper end of the load receiver supporting spider i5 and extend through suitable apertures in a hase casing i9 are surmounted by a load receiving pletter 20.

A pair of posts |91 studded in a similar manner 2,13 in the counterpoise receiver supporting spider il are similarly surmounted by a counterpoise receiver 2l. To maintain the condition of level of Y the spiders I6 and il and the receivers mounted thereon, check links 25 pivotally engesv spiders 'and also a fulcrum pivot 28 iir standing position midway between the two spiders. This Roberval parallelogram is well known in the weighing art, and requires no further description. 3o

Surmounting the `base casing i9, which houses the mechanism assembled on the base plate 9, is a housing 2l having a substantially fan-shaped upper portion, in this housing 2l load counterbalancing mechanism, indicating means and load 35 control means are stationed. To transmit the force resulting from the action of gravity on a load receiver 2U, an auxiliary lever 28 is mounted with its fulcrum pivot 29 upon bearings 'lll which 'are fixed in the upper end of posts 3l fastened lo to and extending upwardly from the base plate 8.

a power pivot 32 which engages a suitable bearing in a stirrup 33 suspended from the lower end of a connecting member 3l. Plvots i5 and .15 36 ilXed in the auxiliary and main levers 28 and l2 respectively, are connected by a loop 3l.

The upper end of the connecting member. M terminates in a thin flexible metallic ribbon 33 which overlies and is fastened to the upper pon so tion of the arcuate face of a sector 39. lIhis sector forms a part of load counterbalancing pendulum 40, which by means of a fulcrum pivot 4I is mounted upon bearings 42, suitably posilioned vin the interior of the housing 21. his u load counterbalancing pendulum also includes a body portion v43 into which a stem 44 is studded and on which a pendulum weight 45 is' threaded. An indicating and controlling member in the form of a "hand 4l vis fastened by means of screws 48 to an upwardly extending portion i8 of the pendulum body 43. The upper end of the hand 4l is in the form of a flag-like paddle i9 having a character 50 marked thereon which is intended to register with a similar character 5l,

marked on a chart 52 stationed within the housing 2l immediately above andin the plane of the hand 4l, when the weight determining portion of this device is in equilibrium. f

To control the amplitude of the impulses ofl the reciprocating motor 8, for reasons which will hereinafter become clear, I employ a photoelectric element 53 yand a cooperating light source 54. v".li'he photoelectric element 53 is completely enclosed in a casing 55, which is mounted on the back wall of housing 2l, so that a cylindrical extension 58 of the casing 55 projects through an aperture in this back wall. The face of this extension 55 is positioned immediately below and slightly back of the plane of the chart and the path of the paddle-like portion of the hand lll. To enable light from the source d to impinge upon the light sensitive surface of the element 58, a narrow slot 5l is pierced through the face of the extending portion 5S of casing 55.

The conveyor 5 shown in Figures I and II, comprises an endless belt 59 passing over rollers 59 and 80, mounted on shafts 5i and 52 respectively; these shafts are fulcrumed in channel shaped members 53 positioned transversely on the load receiver 25. To actuate this conveyor a constant speed synchronous electric motor 88 is mounted on the load receiver 20. A belt 85 engaging a pulley B5 secured to shaft 8l of the motor 53 engages a pulley 54 on the roller shaft 5l and rotates the roller 59 mounted thereon. Synchronous motors having a wide range of speeds are obtainable, so that with either inbuilt or external gears and/or suitable belt 'pulley ratios almost any desired conveyor belt speed may be had.

The weight of this synchronous motor 58 and the conveyor mechanism 5, when mounted on the commodity platter, is counterbalanced when the scale is assembled so that the indicium 50 of the hand 41 is in registry with the indicium 5i inarked on the chart 52, when there is neither a load on the belt 58 nor a weight on the counterpoise receiver 2l, or when such loads are equal.

AThe electrical circuits (Figure 4) comprise a source of powe 89 and main leads 'Ill-li, other leads l2 and i8 are connected to the first mentioned leads by wires 'i4 and l5. 'Ihese leads 'l2 and I3 terminate in metallic mercury retained in wells 16 and Tl in a dielectric member 18, stationed on the base casing i9 immediately below the load receiver v20. To a dielectric plate I9 fastened to the underside of the load receiver 20 two pins 80 and 8| are dependingly fastened which dip into the mercury in the wells 78 and 'il respectively; thus forming an anti-friction means for conveying current from the stationary base to f the relatively movable load receiver 20. Short leads 82 and 83 connected to the pins 80 and 8l conduct the current to the poles of the constant speed synchronous motor 68.

Extensions of leads l2 and I3 are adapted to energize a lamp in the illumination source 54 and "the primary winding 84 of a transformer 85.v A

aioaeoo former conveys current of the proper potential ,to the anode of the photoelectric element 53, the cathode of this element is connected by means of a lead 88 to the grid of a thermionic tube 89. A wire 98 attached to one end of coil 9i, surrounding one of the legs of a core 92 of a saturable reactor 93, conducts energy thereto from the secondary winding 87, the other end of this coil 9| is connectedto the plate of the thermionic tube 89 by means of a wire 90. A potentiometer 95, provided in the circuit permits the necessary adjustment of the grid Voltage to be made, for the reasons which are nowso well known that no further description is necessary.

The other leg of thecore 92 of the saturable reactor is surrounded by a coil 95, one end of which is connected to the power lead l2 by a wire 9i; its other end is connected through lead 98 to one end of the stator coil 99 of the reciprocating motor 8, the other end of this coil 99 is connected by alead 00, to the opposite side of the power line. The armature ll of the reciprocating motor 8 is fastened to the support l, which is stationed nearest the coil 99.

In processing operations, for example in blending materials it is necessary that material be furnished at a constant rate of speed per unit of time. The embodimentrof my invention herein described is a substantial improvement of the means hereinbefore employed for this purpose.

Assuming that for a certain operation 1000 poundsl of material are required per hour and that the effective length of the conveyor belt mounted on the platform is 2 feet and also that it travels at the rate of 1000 feet per hour, it is obvious that in order to supply this amount of material in this amount of time each foot of eective length of the belt 58 must constantly feed 1 pound.

In the embodiment of my invention, the means for determining the weight of the material is a scale of the even balance type; the material on the load receiver therefore, must be offset by a poise ofequal weight. Since in this example 2 pounds of material must constantly be on the load receiver, a 2 pound counterpoise weight i02 is placed on the counterpoise receiver 2 i.

Operation The operation of the device is initiated by closing a switch l03 in the leads l@ and l5. vThis energizes the electric circuit, causing the motor 68 to rotate and revolve the endless belt. Simultaneously, coil 99 of the reciprocating motor is energized and the alternate attraction and repulsion of lits armature lill fastened to the support l imparts longitudinal pulsations to the con'- duit 8.

When the counterpoise m2 is placed on the receiverv 2i this weight, resting on one end of the main lever l2 causes the other end of the lever to ascend,

- this relieves the pull on the pendulum 39' and permits pendulum weight 45, (which when the scale y is in equilibrium is partially raised as shown in Figure I) to descend and the hand 4l uncovers the slot 5l entirely, allowing a maximum amount of light to impinge on the photoelectric element.

This, in a manner to be hereinafter described inv greater detail, causespulsations of the greatest amplitude to be impartedto conduit 6. The operator now opens a gate, (not shown which may be of any desired construction) in the spout 3, and the material flows through this spout into the hopper 4, and thence into the conduit 8 which due to the pulsation imparted to it delivers the ma;

arcaico delivered on the belt increases the pull on the connecting member 38 of the pendulum 39 through the hereinbeiore described lever system and connections, causing the pendulum weight 45 to swing outwardly and upwardly and the paddle 49 on the hand 41 to move in front of the slot 51, thus reducing the illumination on the photoelectric element and decreasing the amplitude o f the pulsation of the conduit 6, thereby causing the material to be delivered at a lower rateof speed. This reduction continues until there are 2 pounds of material evenly distributed on the belt, the extension 49 of the indicator 41 has reduced the maximum amount of illumination of the photoelectric element exactly one-half by covering up one-half of the slot 51, and the characters 50 and 5| on the hand and chart respectively are in registry with each other.

When the amount of light impinging on the photoelectric element is diminished the impedance of the element increases, thus reducing the output of the plate of the thermionic tube 89 in the Well known manner. The flux in the magnetizing coil 9| which forms a part of the saturable reactor 93 influences the current owing through the reactance coil 9G which is also a part of the member 93 and in the circuit which energizes the coil 99 of the reciprocating motor, in the Well known manner, causing a drop in the potential, which reduces the amplitude of the pulsations imparted to the conduit. As a result the material in the conduit is conveyed at alower rate of speed. This reduction will continue until the amount of light shining on the photoelectric element is proportional to the amplitude of the pulses, and delivery of the correct amount of l ate to uncover more of the slot 51 and the additional illumination, in the manner hereinbefore described will increase the potential impressed on the coil 99 and increase the amplitude of the pulses .imparted to the conduit 6 until the rate of ilow is again equal to the desired rate.

Since there'are no appreciable time lags in the electric reactions, the corrections are made almost instantaneously, thus insuring an even fiow of the correct amount of material to the belt, and since the motor 68 which drives the belt is synchronous and thus has a constant speed, the correct amount of material at the desired rate of speed is assured.

It will be seen that the embodiments of my invention hereinbefore described are well adapted to fulfill the objects primarily stated. It is to be understood, however, that the invention is susceptible to variation, modification and change within the spirit and the scope of the subjoined claims.

Having described my invention, I claim:

)1. In a device of the class described, in combination, weighing mechanism, means for supplying material in a smooth stream to said weighing mechanism, a -belt conveyor for conveying such material from said weighing mechanism, a

synchronous motor for moving said belt conveyor at a uniform linear footage per minute, and means controlled by said weighing mechanism and controlling said supplying means to maintain the load on said weighing mechanism at substantially constant weight, said belt conveyor and synchronous motor being supported on said weighing mechanism.

2. In a device of the class described, in combin nation, Weighing mechanism, a pulsating conveyor for supplying material in a smooth stream to said weighing mechanism, a belt conveyor for conveying such material from said 'Weighing mechanism, a synchronous motor for moving said belt conveyor at a uniform linear footage per minute, and means controlled by said weighing mechanism and controlling said pulsating conveyor to maintain the load on said `Weighing mechanism at substantially constant Weight, said belt conveyor and synchronous motor being supported on said weighing mechanism.

3. In a device of the class described, in combination, weighing mechanism, a pulsating conveyor for supplying material in a smooth stream to said weighing mechanism, a belt conveyor for conveying such material from said Weighing mechanism, a synchronous motor for moving said belt conveyor at a uniform linear footage per minute, said belt conveyor and synchronous motor being supported on said weighing mechanism, and photosensitive means controlled by said weighing mechanism and controlling said pulsating conveyor to maintain the load on said weighing mechanism at substantially constant weight.

4. In a device of the class described, in combination, weighing mechanism, electroimpulsive feeding means cooperating therewith, said weighing mechanism comprising load-receiving means,

load-counterbalancing mechanism and a hand connected to said load-counterbalancing mechanism, the amplitude of the pulses of said electroimpulsive feeding means being variable, and means controlled by said weighing mechanism forl varying such amplitude, said means comprising a photosensitive element, an opaque screen mounted to shield said photosensitive element, there being a slot in said screen adjacent the path of said hand, said slot being substantially angular to the position of one edge of said hand whereby movement of said hand varies the amount of light passing through said slot substantially proportionally to the Weight of a load on said load-receiving means.

5. In a, device of the class described, in combination, weighing mechanism, a pulsating conveyor for supplying material in a smooth stream to said weighing mechanism, a belt conveyor for conveying such material from said weighing mechanism, means for moving said belt conveyor at a uniform linear footage per minute, said belt conveyor being so supported by said weighing mechanism that said weighing mechanism is uniniiuenced by the means for moving said belt conveyor, and means controlled by said Weighing mechanism and controlling s aid pulsating conveyor to maintain the load' on said weighing mechanism at substantially constant weight.

MARK A. WECKERLY. 

